[Twisted-Python] Bloody Twisted VFS

[Andy Gayton]

Hey guys,

I'm really keen to get twisted.vfs to a stable point that is
acceptably releasable.

There's 6 tickets to knock off to get it to this state:

This ticket will give an easily runnable vfs server, which'll be
useful for experimenting with vfs as it is worked on:

* http://twistedmatrix.com/trac/ticket/2821

This ticket ports the backend vfs interface to be firstly async, and
also, not quite so lame:

* http://twistedmatrix.com/trac/ticket/2815

Then we can port the 3 currently supported protocols over to use the
new backend interface:

* http://twistedmatrix.com/trac/ticket/2816
* http://twistedmatrix.com/trac/ticket/2817
* http://twistedmatrix.com/trac/ticket/2818

And finally once everything is ported, there can be a good clean up:

* http://twistedmatrix.com/trac/ticket/2819

Exarkun also has some good suggestions for #2815.  I've gone ahead and
fixed the ones mentioned - but this is defining an interface - which
isn't something to lock into lightly.

As he says:

'What these interfaces should actually say is still an open question,
I think. This would probably benefit from some real-time conversation
with various interested parties involved. You've probably already
noticed IFTPShell which is one take on this interface (it's not
exactly the same shape, but many of the ideas apply here).'

is very reasonable.  Just before the first .au sprint I put a bit of
time into this - and conch's IConchUser interface seemed to be a
better base for vfs than IFTPShell - but this is something that could
use more discussion.

I've quit my job in LA that's sucked up all my life for the last 2 or
so years and I'm now on a road trip around the US. I've hauled up in
vermont for the week to catch up on a bunch of stuff - top of the list
is to try and get vfs up to scratch finally. I'm planning to be in the
Massachusetts area next week - again for around a week.

If anyone is available to meet up and hash this out, that'd be awesome.

It feels like if we can hit #2815 on the head, the rest will fall into
place.  Therve has been awesome at chugging through previous vfs stuff
- porting protocols to use the agreed upon backend interface should be
straight forward.

cheers,
Andy.